Ortho-aminoaldehydes and ortho-aminoketones of the anthraquinone series and process of preparing them



Patented Nov. 3, 1931 UNITED STATES PATENT .QFFICE KARL WILKE, F FRANK ?ORT-ON-THE-IIIAIN-HOCHST,.GERMANY, ASSIGNOR T0 GEN- ERAL ANILINE WORKS, INC., OF NEW YORK, N. .Y., A CORPORATION OF DELAWARE ORTHO-AMINOALDEHYDES AND ORTHO-AMINOKETONES OF THE 'ANTHRAQUINONE SERIES AND PROCESS QF'PREPAEING"THEM No Drawing. Original application filed March 3, 1927, Serial No; 172,555 and in'Ge rmany March 8, 1926.

Divided and this application filed April 11, 1929. Serial No. 354,439.

My present invention relates to ortho-amino-ketones of the anthraquinone series and to a process of preparing them. More particularly my invention relates to the new 5 compounds of the following general formula:

0 NHz wherein R stands for an alkyl group.

I have found that ortho-aminoaldehydes and ortho-amino-ketones of the anthraquinone series are obtained by treating with a reducing agent as for instance with sodium hydrosulfite or with ferrous sulfate the reaction products which are formed for instance by the action of fuming sulfuric acid upon 1nitro-2-alkyl anthraquinones at a low temperature and which are insoluble in cold alkalies and distinguished by their great reactivity (see for instance U. S. Patent No.

1,417,875). The products corresponding to the 1-nitro-2-methyl anthraquinones are thus converted into the ortho-amino aldehydes, the products corresponding to the l-nitro- Q-ethyl anthraquinones, however, into the ortho-aminoketones. This reaction shows that the above-mentioned intermediate products are anthraquinone-isoxazoles and proves the correctness of the supposition as regards their constitution which could hitherto only be deduced from the empiric composition determined by analysis. The manner in which these products are formed does not indicate a priori that they constitute isoxazole derivatives. Nor could it be foreseen whether and how far an isoxazole of the anthraquinone series would have the well known properties of the isoXazoles of other classes of substances.

The preparation of the anthraquinone-isloxazoles may advantageously be combined with the preparation of amino anth'raquinone aldehydes and: amino anthraquinone ketones so that only a single operation is required in each case.

The following example serves to illustrate it thereto; the parts are by weight.

Preparation of 1-amino2-acetyl anthra- 1 part of anthraquinone-1.2-n1ethyl isoXazole (obtainable by causing fuming sulfuric acid to act upon l-nitro-Q-ethyl anthraquinone) is mixed with 2 parts of sodium hydrosulfite 1 in an aqueous ammoniacal solution and the mixture is heated on the water bath, while excluding air, until the mass is dissolved. By subsequently introducing air into the filtered solution the l-amino-Q-acetyl anthraquinone is obtained, which, when recrystallized from glacial acetic acid, forms coarse red needles melting at 220 C. It dissolves in an ammoniacal hydrosuliite solution to a reddish-yellow, in a caustic alkaline solution to a brown solution.

This is adivision of my co-pending application Serial No. 172,555 filed on March 3, 1927.

I claim:

l. The process which comprises subjecting an anthraquinone-l.Q-alkyl-isoxazole compound to the action of a reducing agent.

2. The process which comprises reducing an anthraquinone-LQ-alkyl-isoxazole compound with ferrous sulfate.

3. The process which comprises subjecting anthraquinone-l.Q-methyl-isoxazole to the action of a reducing agent.

9 my invention, but it is not intended to limit i 4. The process which comprises reducing anthraquinone-1.2-methyl-isoxazole with ferrous sulfate.

5. As new products, compounds of the following formula:

wherein R stands for an alkyl group.

6. As a new product, l-amino-Q-acetyl anthraquinone crystallizing from glacial acetic acid in the form of coarse red needles melting at 220 C. and dissolving in an animoniacal hydrosulfite solution to a, reddish-yellow, in a caustic alkaline solution to a brown solution.

In testimony whereof, I aflix my signature.

KARL WILKE. 

